i915: 3.1.0-rc3+: WARNING: at fs/sysfs/dir.c:455 sysfs_add_one+0xb8/0xf0()

[Sergei Trofimovich]

Around -rc2+ i've noticed the following warning in dmesg [1]

> WARNING: at fs/sysfs/dir.c:455 sysfs_add_one+0xb8/0xf0()
> sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight'

It tries to register backlight twice, so fails miserably.
The machine is compaq-2510p with 965GM.

Reverting commit aaa6fd2a004147bf32fce05720938236de3361d9 helps.
("Not all systems expose a firmware or platform mechanism for changing
the backlight intensity on i915,  so add native driver support.")

Attached dmesg before reverting the patch and after.

Thanks!

[1]:
------------[ cut here ]------------
WARNING: at fs/sysfs/dir.c:455 sysfs_add_one+0xb8/0xf0()
Hardware name: HP Compaq 2510p Notebook PC
sysfs: cannot create duplicate filename '/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight'
Modules linked in: i915(+) drm_kms_helper drm sdhci_pci sdhci iwl4965 yenta_socket pcmcia_core iwl_legacy mmc_core mac80211 snd_hda_codec_analog processor i2c_algo_bit thermal pcmcia_
rsrc container cfg80211 e1000e battery button ac rfkill snd_hda_intel fan snd_hda_codec snd_hwdep
Pid: 828, comm: modprobe Not tainted 3.1.0-rc2-00169-g5ccc387 #137
Call Trace:
 [<ffffffff8103e7ba>] warn_slowpath_common+0x7a/0xb0
 [<ffffffff8103e891>] warn_slowpath_fmt+0x41/0x50
 [<ffffffff81130878>] sysfs_add_one+0xb8/0xf0
 [<ffffffff8113136c>] create_dir+0x7c/0xd0
 [<ffffffff8113143c>] sysfs_create_dir+0x7c/0xd0
 [<ffffffff81035b7d>] ? sub_preempt_count+0x9d/0xd0
 [<ffffffff8123302d>] kobject_add_internal+0xbd/0x200
 [<ffffffff81233288>] kobject_add_varg+0x38/0x60
 [<ffffffff81233364>] kobject_add+0x44/0x70
 [<ffffffff81232e4a>] ? kobject_get+0x1a/0x30
 [<ffffffff812cb218>] device_add+0x98/0x690
 [<ffffffff812d4d81>] ? pm_runtime_init+0xd1/0xe0
 [<ffffffff812d3ef9>] ? device_pm_init+0x59/0x80
 [<ffffffff812cb829>] device_register+0x19/0x20
 [<ffffffff81274021>] backlight_device_register+0xf1/0x1c0
 [<ffffffffa0281e53>] intel_panel_setup_backlight+0x73/0xf0 [i915]
 [<ffffffffa027640b>] ? intel_crt_init+0xeb/0x1d0 [i915]
 [<ffffffffa026ddc9>] intel_modeset_init+0x7c9/0x1100 [i915]
 [<ffffffffa024adc1>] i915_driver_load+0xc81/0x1170 [i915]
 [<ffffffffa01fe251>] ? drm_sysfs_device_add+0x81/0xb0 [drm]
 [<ffffffff81233cb7>] ? kobject_uevent_env+0x1b7/0x470
 [<ffffffffa01fb203>] ? drm_get_minor+0x243/0x300 [drm]
 [<ffffffffa01fd3b8>] drm_get_pci_dev+0x188/0x2b0 [drm]
 [<ffffffff81035b7d>] ? sub_preempt_count+0x9d/0xd0
 [<ffffffffa028e4a0>] i915_pci_probe+0x1b/0x13f [i915]
 [<ffffffff81253aea>] local_pci_probe+0x5a/0xd0
 [<ffffffff81254680>] pci_device_probe+0x80/0xb0
 [<ffffffff812cd71a>] ? driver_sysfs_add+0x7a/0xb0
 [<ffffffff812cd866>] driver_probe_device+0x96/0x1c0
 [<ffffffff812cd990>] ? driver_probe_device+0x1c0/0x1c0
 [<ffffffff812cda23>] __driver_attach+0x93/0xa0
 [<ffffffff812cd990>] ? driver_probe_device+0x1c0/0x1c0
 [<ffffffff812ccf58>] bus_for_each_dev+0x68/0x90
 [<ffffffff812cd699>] driver_attach+0x19/0x20
 [<ffffffff812cc808>] bus_add_driver+0x198/0x260
 [<ffffffff812ce078>] driver_register+0x78/0x140
 [<ffffffff81254931>] __pci_register_driver+0x51/0xd0
 [<ffffffffa01fd5f9>] drm_pci_init+0x119/0x130 [drm]
 [<ffffffffa02ae000>] ? 0xffffffffa02adfff
 [<ffffffffa02ae08b>] i915_init+0x8b/0x8d [i915]
 [<ffffffff810001ce>] do_one_initcall+0x3e/0x170
 [<ffffffff81075b9a>] sys_init_module+0x8a/0x1e0
 [<ffffffff814325fb>] system_call_fastpath+0x16/0x1b
---[ end trace 1c7dd79996e79e7a ]---

-- 

  Sergei
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